Chapter 587 The authority is really wrong!
".Authority is wrong?"
In this secret room underground.
As Xu Yun said these words.
This time.
The one who was shocked was no longer Lao Guo, but
All members of the project team gathered around the table, including Lu Guangda, the two men who were at war with each other before, and others.
There is no other reason.
What Gein Xu Yun said was really impactful.
Is Norris Bradbury's design theory wrong?
How is this possible?
To know.
Norris Bradbury was Oppenheimer's personal manager of the Manhattan Project. He personally assembled the plutonium detonator in the center of the first atomic bomb in human history.
It can be said that.
With the exception of Oppenheimer, no one knew more about atomic bomb theory than Norris Bradbury.
This is a great man who will surely go down in the history of human science.
It is like a big mountain lying in front of everyone. Any pedestrian who sees this peak will only sigh with admiration - even Lao Guo and Lu Guangda.
At least for the moment.
The result was unexpected.
Xu Yun, the 'Foolish Old Man', suddenly jumped out and pointed at the mountain and said that its location was wrong and it shouldn't be there.
This is obviously quite an astonishing statement.
At this time, Xu Yun seemed to have a vague attitude of not saying anything surprising. Facing the surprised people, he continued to say:
"Gong Guo, Director Lu, why can't authority be wrong?"
"It is true that Norris Bradbury and Oppenheimer completed the Trinity and Manhattan Projects, and there is no doubt about their ability."
"But don't forget, this stationary critical state model is just a cutting-edge theory for atomic bomb research across the sea, and has not been technically implemented."
"So in theory, why couldn't Norris Bradbury be wrong?"
"Even."
Speaking of which.
Xu Yun paused deliberately and looked around:
"Is it possible that the theory across the sea cannot be iterated in application because some of the links are actually problematic? That is why it cannot be adapted in reality?"
Swish——
Xu Yun finished speaking.
The sound of pindrops suddenly became audible at the edge of the table.
This silence, contrasted with the sounds of calculations and discussions further away, formed an extremely subtle picture.
"."
A long time passed.
Lu Guangda just recovered from the surprise and looked at each other with Lao Guo beside him.
Not an exaggeration.
Xu Yun's words were so impactful that they even shook their cognition.
But on the other hand.
Undeniable.
Although what Xu Yun said is somewhat difficult to accept cognitively, it is indeed logically possible.
Based on information proactively disclosed by the other side of the sea.
The Manhattan Project used an approximate solution to the neutron transport equation, which is a parallel SN algorithm in a two-dimensional spherical coordinate system.
This solution uses spatial-angular parallelism calculation that combines regional decomposition and parallel pipelines, and the parallel efficiency is about 52%.
At the same time, this method has a high error rate. The higher the magnitude, the more likely errors will occur, and it will inevitably be eliminated.
So it's the same as choosing to develop a more difficult uranium bomb instead of a plutonium bomb.
The theory team led by Lu Guangda rejected this parallel algorithm and prepared to come up with a theory that could be used in the long term.
By the way.
Later, Gaul did not raise a white flag in this regard, and also gave up the parallel SN algorithm - but John Bull took a clever trick and continued to use this method.
Then a while passed.
Lu Guangda took a deep breath, forced himself to calm down, and asked Xu Yun:
"Comrade Han Li, since you think there is something wrong with this model, can you find out what's wrong?"
"After all, there is no basis for words, everything must be based on evidence."
Xu Yun pondered for a moment after hearing this, and finally shook his head slightly:
"Director Lu, I'm sorry. Due to limited time, I definitely won't be able to find out the core error for you."
"After all, I am not an omniscient and omnipotent god or a time traveler from the future. I can know everything in advance."
"But what I am sure of is that at least there must be a problem here."
Say it.
Xu Yun stretched out his index finger and pointed lightly at a certain area on the calculation paper.
Lu Guangda subconsciously poked his head and took a few glances, and was slightly startled:
"High compression thermonuclear fusion zone?"
Xu Yun nodded, picked up the pen and drew a horizontal line on a parameter, and began to explain:
"Look here, the flow density of the collapse density is 1.533, right?"
Lao Guo nodded.
Xu Yun then took up his pen and wrote:
"Look, we first define a transport mean free path and insert the cosine of the mean scattering angle. The neutron will have an extrapolation distance d=2λtr/3."
"For the root of the reciprocal of the characteristic coefficient, let's not talk about the specific value. The number of extrapolated neutrons must be smaller than the number of divergent neutrons in the central area A. So how can the calculated number be a number greater than 1?"
"So clearly Norris Bradbury must have undercalculated some divergent scenario."
Lu Guangda's pupils suddenly shrank.
Mentioned earlier.
Because this framework was calculated by Norris Bradbury.
Therefore, after getting the document and translating it, Lu Guangda and others simply checked it and used it directly.
After all, this document has promoted the progress of many stuck projects before, and it cannot be something that has been tampered with like a gas exchange membrane.
This approach is like using a computer to design a physical model, and one day you just get a host.
After preliminary testing of this host, there are no problems with its functions such as running scores, starting up, surfing the Internet, and downloading movies.
Therefore, although you are curious about its internal structure, because the design of the physical model is important, you just start using it without paying attention to the specific parts.
And the link Xu Yun pointed out now is equivalent to telling them:
Dear, there is a problem with a certain thread of the CPU of this computer - it is not deliberately tampered with, but the manufacturer has made mistakes in the production process, and even the manufacturer itself may not know it~
Think of this.
Lu Guangda couldn't help but pick up the manuscript paper and pen in front of Xu Yun and read it carefully.
As everyone knows.
The framework of the neutron transport equation is very broad, but there are not many particularly important concepts in it, and there are only about a dozen of them.
And in these concepts.
Logarithmic reduction is undoubtedly a very important concept.
It refers to the energy loss rate of neutrons when moving in matter, and the expression is u=lnE0/E.
Where E0 is the energy before neutron scattering, E is the energy after neutron scattering, and u is the logarithmic energy drop.
After having the concept of being able to drop.
Then we can define the average logarithmic energy drop of a certain substance.
That is, the average energy drop produced by each scattering between a neutron and such an atom:
ξ=Δu≈2/（A+2/3）.
This is an approximate calculation formula for the average energy drop and can be used for atoms with an atomic weight A greater than 10.
In this way, you can calculate how many times the neutrons need to scatter on average to drop from E0 to the specified E when a material made of a certain atom is used as the target:
Nc=u，ξ=lnE0lnEξ.
Give an example.
The energy drop of neutrons slowing down from 2MeV (the average energy of fission neutrons) to 0.0253eV is u=lnE1/E2=18.1856.
Of course.
The concept of energy reduction has also undergone some conceptual iterations in later generations, and has been more applied in the field of reactors.
However, this concept is still very mainstream in this era, and it will not be updated until the 1980s, both at home and abroad.
And for a reduced energy neutron.
Its 'life' goes through two processes: slowing down and diffusion.
The average time of slowing down is called slowing time, and the average time of diffusion is called diffusion time.
The neutron lifetime can be expressed as the slowing down time plus the diffusion time - this should be regarded as the addition of difficulty in the first grade of elementary school.
In other words.
The time a neutron exists in a nuclear reaction can be obtained by dividing the free path by the speed of motion, that is, integrating the average energy drop.
Wait until this step.
A crucial concept emerges.
This is also a concept that appears widely in quantum mechanics, fluid mechanics, and electrodynamics:
Flow density, j=ρv.
The so-called flow density refers to a quantity that can be used to describe changes in physical quantities within the system.
You can tell its meaning from its appearance:
Density times velocity.
Density represents elements, while velocity is perpendicular to the system boundary, which represents elements leaving or entering the system.
in nuclear engineering.
If the neutron density is n, then there is a neutron flux density, which is also the neutron flow density neutron = nv neutron/(ms).
That is, the number of neutrons passing through a unit area per second.
Since the neutron flux density can measure the changes in the neutron level in the system, and combined with the macroscopic cross-section Σ, it has the physical meaning of reaction probability, so the nuclear reaction rate R neutron R = Σ neutron/(ms) can be defined.
This represents the probability of a nuclear reaction occurring, that is, how many neutrons are reacted per unit time per unit volume.
The concept is very simple and easy to understand.
What Xu Yun pointed out was that the difference in neutron density between the two steps was abnormal.
Let’s still give an example that is less accurate but easier to understand to describe this situation:
Suppose your name is Li Ziming and you are studying in Class 2 of a primary school.
Your class is on the third floor of the teaching building. There are dozens of identical classrooms in the entire teaching building, and there is only one entrance on the first floor.
Then the steps for everyone to go to class must be like this:
First pass through the entrance on the first floor, walk along the stairs to the respective floors, and then enter your class.
That is.
within a certain period of time.
The number of people entering the classroom of Class 2 of Grade 3 must be far smaller than the total number of people entering the teaching building from the first floor.
In other words.
The ratio between the two is not just a few to a few, but it must be less than or far less than 1 - if there are 50 people in a class, there will be at least hundreds of people entering the teaching building.
But the framework calculated by Norris Bradbury is different.
The ratio it shows is greater than 1, which is equivalent to more people walking into the class than walking into the teaching building, so there is obviously something wrong.
"n(r,t/)t=S(r,t)Σa(r,t)J(r,t)"
"Add a steady-state situation/t=0, then we have d2(r)dr2+2rd(r)dr(r)L2=0"
"Introducing Fick's law... So using the neutron flux density (r, t) as the function to be determined, rewrite the continuity equation as 1/v/t=SΣa+D4"
Write here.
Lu Guangda's pen tip suddenly exerted force and poked a hole in the paper.
But Lu Guangda, who was usually extremely frugal, did not show any distressed expression this time, but stared at the formula he had calculated.
1/v（/t）=SΣa+D4.
This formula may seem unfamiliar at first glance.
But if you remove the 4 at the end of [4], many smart students will recognize it.
That’s right!
This is the starting point of all nuclear engineering and one of the most important equations in the entire nuclear engineering physics
Neutron diffusion equation.
It describes the change of neutron flux density distribution, and is a second-order differential equation in space. In some cases, it can be turned into the Helmholtz equation to provide a wave solution.
At the same time, it is a first-order differential equation in time, which can obtain monotonic development in time.
Generally speaking.
For any complete framework, you can deduce the correct expression of this formula.
But
Now Lu Guangda's results showed an extra 4!
There are more than 4 in differential equations. Any further explanation of this concept will lead to criticism.
all in all.
This is an impossible situation in any case!
To know.
These derivations by the Theoretical Department are not all mathematical calculations. Many of the parameters they calculate come from the experimental teams in the application zone - otherwise the rabbits would not have to build a detonation laboratory.
For example, the parameters used by Lu Guangda and others this time.
Some of these parameters come from files sent back from across the sea. The files originally belonged to some national experimental institutions.
Some of it comes from the information they brought back when they went to Maozi for further study seven or eight years ago, such as the Petrov reactor.
There are also some from the neutron physics laboratory of the Seventh Branch Factory, which is in the workshop next to Lu Guangda and the others.
Many of these data are parameters of real nuclear explosions, which are facts that have already happened - no matter how bad they are, they are cold explosion data.
There are problems with the results derived from these facts, and it is obviously not the fault of the data.
That is to say
There are indeed some errors and omissions in Norris Bradbury’s framework!
The big guys at the scene were all domestic elites, so they soon realized this one after another.
See this situation.
Xu Yun did not need to remind him again.
Lu Guangda looked at everyone present, showing his decisive side, and quickly gave various instructions:
"Xilai, you should immediately lead the second group to reexamine the problem of the cosine of the average scattering angle!"
"Comrade Chen Rui, you are responsible for verifying the dimensions of the diffusion length."
"Lao Hua, go and calculate whether the superposition state of eigenwaves is continuous - well, try it without introducing an effective proliferation coefficient."
"Lao An, you take Xiaogao and the others."
Looking at Lu Guangda who quickly entered the state, Xu Yun couldn't help but feel a trace of emotion in his heart.
He is indeed the boss who coordinates the theory department.
To know.
To avoid revealing too many abnormalities.
This time Xu Yun only gave an error that seemed obvious at first glance, but actually involved a wide range of things.
There are at least twenty or thirty calculation modules for radiation from this error point. The complexity alone far exceeds the number of teams in this room.
The result was unexpected.
Lu Guangda actually made arrangements so quickly, and the directions he mentioned are at least 80% correct!
This is purely a category of professional instinct, and requires a very solid and strong accumulation of knowledge to achieve this step.
Even in the world at this time, there are not many people who have this kind of strategic instinct.
There is definitely a number with five fingers, but not necessarily with ten fingers.
Soon followed.
The entire laboratory was quickly mobilized.
Among them, the most exciting ones were undoubtedly the two big guys who had quarreled before and their team members.
That is, Hua Yun, who was the leader of the second group of the Theory Department, and Ma Ruiping, who was the leader of the third group.
Hua Yun is currently one of the few big names in China who has obtained doctorates in theoretical physics and functional analysis at the same time. Although he is not a member of the academic department, he is very capable.
In the field of functional analysis, he can even be said to be the first person in the base or even in the country!
Ma Ruiping is an applied mathematics expert who graduated from Michigan State University. Due to his solid English speaking and writing skills, he is now mainly responsible for the translation of foreign language journals.
Although Ma Ruiping was not elected as an academician in later generations, he still had an ordinary deputy senior professional title until his retirement, and it was not even officially declassified until 2022.
However, in the entire 596 project, he personally translated 70% of the foreign language documents, which can be said to be an outstanding contribution.
Previously, it was because the problem was not found.
Hua Yun, Ma Ruiping and the team behind them all received a lot of pressure - otherwise they wouldn't question each other.
This kind of doubt is firstly based on self-confidence in one's own ability, and secondly, because the analysis of this document is too important, and no one wants to take the blame.
Now that they have discovered the culprit who caused them to be hacked, how can they not be excited?
So it's quick.
The entire project team stopped what they were doing and started doing calculations.
"Ci(r,t)t=βik∞Σa(r,t)λiCi(r,t)i=1,2,3,.,m Brother Wang, please give me the file No. 3 over there at Mao Xiong. ! ”
"Everyone, the space part is the Helmholtz equation. The general solution is the superposition of a series of standing waves, that is, the superposition state of a series of eigenwaves. So if you want to ignore it and study changes in time, it is equivalent to assuming the entire process. The neutron flux density constitutes a whole wave, and the changes at each point are synchronous, then we should"
"Xiao Zhao, would you like to go to the toilet together later?"
"0.557, 0.559, 8.322, report, there is an obvious bump in the calculation process!"
"Great, what is the density vector?"
"There is only a rough range, it should be around 18.5-19.7!"
"Aba Aba."
Looking at the lively scene.
Xu Yun couldn't help but cast his eyes on the piece of paper in front of Lu Guangda again.
That is.
The record contains an English copy by Norris Bradbury.
to be honest.
In the year 2023 of the hereafter.
Xu Yun did not know that this document was the existence of the stationary subcritical state model designed by Norris Bradbury.
This is actually quite normal.
After all, there are too many twists and turns and stories in the development process of nuclear weapons. Many things have not been declassified even by 2023 - some may have been declassified, but they have not been fully disclosed, making it very complicated to inquire.
What Xu Yun could know was only the surface level of these things, that is, many comrades sacrificed their precious lives to protect the smooth transportation of those foreign language journals back to China.
As for the general contents of these journals, he could not fully understand them.
But on the other hand.
Based on some of the rabbits' later achievements, Xu Yun was able to roughly compare certain situations.
For example, the correction of the well-known supercritical amplification effect.
Xu Yun didn't know which incident was the result of this, and he couldn't even remember clearly who was the leader of the team that corrected it.
But if one day we encounter an incident related to the critical adjustment error of group parameters, then this incident must be related to the correction of the supercritical amplification effect.
It's like one day when you traveled to a certain era and didn't know anything about the scenery and people around you. Then someone next to you said, "Commander, Huanggutun is just ahead." You can definitely guess which day it is. several years.
The same is true now.
Although Xu Yun did not know in advance the stationary critical state model designed by Norris Bradbury.
But it is not difficult to judge from this error point that this error must be related to that incident.
And if that’s really the case
Think of this.
Xu Yun's heart suddenly beat rapidly.
etc!
If the conditions are right.
It seems like maybe we can take the opportunity to do something big again?
If that can happen.
The help to the rabbits may not be inferior to defeating U2!
Then Xu Yun thought carefully about the information that later generations learned, and felt more and more that this matter had something to do with it.
Of course.
This matter is of great importance and involves many aspects. It is no less difficult than the later generation Xu Yun who updated 50,000 words a day.
So how to operate it requires careful consideration.
At least
From the current point of view.
Even if you include what Lu Guangda and the others are verifying, this idea still lacks a piece of the puzzle.
Two hours later.
Hua Yun, who was not far away, suddenly raised his head and shouted to Lu Guangda:
"Director Lu, I found the cause of the problem!"
Lu Guangda's expression suddenly straightened and he asked quickly:
"What's the reason?"
Hua Yun quickly brought the results calculated by his team to Lu Guangda's side and slammed it onto the table:
"Director Lu, look!"
"The stationary subcritical state model designed by Norris Bradbury is a weak field approximation, which can only achieve a good description effect in the region where (r, t) changes slowly."
< br>
"But look at these three data, which are the experimental results of Mao Xiong, across the sea and our own."
"These results show that the source, that is, S(r, t) and the neutron flux density (r, t) will interact nonlinearly."
"In addition, in areas very close to the source, and areas where (r, t) changes drastically such as near the control rod, the changes are essentially nonlinear!"
"That is to say, the Norris Bradbury across the sea used a linear equation to describe a nonlinear situation!"
"Authority. Something went wrong!"
Note:
I replaced part of the process with reactor principles, for reasons everyone knows. (End of chapter)